Preheat oven to 400 degrees.
Prepare a rimmed baking sheet with parchment paper. Rinse and scrub potatoes under cold water. Pat dry.
On a cutting board, place two wooden spoons with handles the same thickness on either side of a potato.
With a sharp knife, cut the potatoes into thin slices, about 1/4-inch thick. The spoons will prevent you from cutting all the way through to the bottom of the potato.
Repeat with other potatoes. Cut the butter into thin slices and place a slice of butter into every other slit in the potatoes. In the other slit, insert a piece of Parmigiano cheese, so that it alternates. Butter, cheese, butter, cheese etc.
Sprinkle each potato evenly with the garlic powder and salt. Drizzle each with olive oil.
Bake for 45 minutes.
Remove baking sheet from the oven and drizzle each potato with the heavy cream.
Sprinkle shredded cheese over the top of each, then place back in the oven for another 10-12 more minutes.
Serve warm with plain Greek yogurt and green onions, if desired.
Compliments of 365 Days of Baking and More